This study examined the applicability of imagery rehearsal therapy (IRT) to children with frequent nightmares. Eleven boys and 9 girls aged 9 to 11, with moderate to severe primary nightmares (1 or more per week for 6 months) and without posttraumatic stress disorder, were randomly divided into an imagery rehearsal treatment group (n = 9) or a waiting-list (n = 11) group. ANCOVA with repeated measures revealed that, following a baseline period, IRT reduced the frequency of nightmares (p < .04; eta(2) = 0.22) in the treated group compared to the waiting-list group. This reduction was maintained over a 9-month follow-up. The effects of IRT on post-nightmare state distress could not be assessed due to low nightmare incidences. However, retrospective trait nightmare distress was not significantly reduced. Future research is needed to validate this simple approach for nightmare reduction and to evaluate its potential for the reduction of the associated nightmare distress.